1. Technical Field
Embodiments of the present disclosure relate to light source driving devices, and particularly to a light source driving device with a fault detecting function.
2. Description of Related Art
FIG. 4 is a light source driving device with a fault detecting function. A power stage circuit 30 converts an external electrical signal to an alternating current (AC) signal. The AC signal is converted to a sine-wave signal to drive the light source 10 via a transformer circuit 20. A control circuit 40 is connected to the power stage circuit 30 to control output of the power stage circuit 30. A voltage level comparison circuit 50 is connected to the control circuit 40 to check whether a difference between a lamp status feedback signal and a benchmark voltage is within a predefined range so as to determine whether the light source 10 is nonfunctional and output a fault signal. The control circuit 40 turns off the output of the power stage circuit 30 based on the fault signal.
The benchmark voltage often uses a fixed bias voltage. However, the lamp status feedback signal often varies according to a lamp brightness control signal or a surrounding temperature. Because the voltage level comparison circuit 50 compares the varied lamp status feedback signal to the benchmark voltage of a fixed bias voltage, unreliable detection of faults may occur. Therefore, the light source driving device cannot exactly determine whether the light source 10 is nonfunctional.